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General discussion - Session 5 Recommendations and future prospects for plant breeding to maintain or improve the nutritive value of crop residues
Onim: We need to arrive at a definition of what constitutes a crop residue. For instance, thinnings may be fed to animals before harvest.
Kossila: Even materials such as potato peelings are, in my opinion, crop residues.
Said: Byproducts are mostly fed with supplements, such as urea/molasses, which may influence intake. Clearly the methodology for intake determination needs to be standardised.
Berhane: I think that the general statement proposed for adoption by the meeting is too strongly worded. I do not believe that the CG centres should put more emphasis on crop residue value.
Van Soest: The statement does not diminish the importance of grain production in any way. However, it may not be appropriate to list priority crops for investigation of crop residues and there may be many important benefits from a particular variety before residue value should be considered.
Gupta: Attempts should be made to find morphological characteristics that are, associated with feeding values of crop residues.
Jenkins: It would be useful to have correlated traits with which plant breeders could work.
Van Soest: Whatever selection methods are chosen it is important that they are compatible with the objectives of the work.
Gupta: If the traits related to nutritive value were known even as many as 10,000 samples would not be too large a number in a plant breeding programme. I agree that one should avoid screening entire gene banks.
Jenkins: I believe it would be unwise to be specific on the scale of any evaluation programme.
Van Soest: It is usually necessary to use plant criteria including grain yield to narrow down the number of entries that can be fully evaluated in the laboratory to about 200. Subsequently residues from no more than 12 varieties could be subjected to full animal evaluation. In addition one could include a few parent lines with promising value. Perhaps I should also mention that work on an European Community project being conducted in the Netherlands has shown that varieties of maize grown in Europe have digestibilities of residues 10 units higher than those grown in the USA and this does not appear to be an environmental effect.
Berhane: In my previous comments I was not questioning the practical value of investigating variation in crop residue quality. However I would not see this as a primary responsibility of the CG centres, which should concentrate on grain yield and grain quality. To bring in crop residue value as an index of selection would not serve the immediate mandate of CIMMYT to increase yields of wheat and maize.
Fussell: The question of whether crop residues are important needs to be put to the ultimate user of new varieties, the farmer. More information is needed as to what is happening at the farmer level, through more feedback from extension services.
Witcombe: Ground-level surveys are needed, involving cooperation between economists and animal nutritionists, in order to obtain farmers' perceptions regarding the acceptability of new varieties. This should form a major recommendation.
Little: We need to know the base-line considerations of farmers concerning crop residues.
Onim: There appears to be a need to introduce animal nutritionists at crop research centres.
McAllan: It would concern me that the number of materials to be evaluated may exceed the capacity of animal nutrition facilities. Should animal nutritionists be in a monitoring or collaborative role?
Fussell: I would suggest looking at current varieties first. For example in West Africa only five or six millet varieties would need to be fully evaluated.
Reed: Perhaps we are putting too much emphasis on the need for farmer surveys. For instance we already know that the digestibility of barley straw in the Ethiopian highlands is 55% whereas in Europe it is only 35%. Information is already available for groundnut residues in Senegal. I consider it more important to deal with the effects of crop management on residue values so that they are at least capable of maintaining the animals.
Little: Emphasis needs to be placed on finding an appropriate method of evaluation for particular crops. Subsequently such tests could then be run by laboratory technicians.
Van Soest: I think that one will need more than one parameter to effectively identify varieties with superior crop residue value. The use of plant criteria followed by investigations of crop residue value would seem to be the best means of tackling the large number of entries available.
Jenkins: It would be useful to have contributions from national programme representatives.
Kebede: In Ethiopia I consider that we must continue to give priority to grain production, to consider residue value may be a luxury. Yet this workshop has been an eye-opener and, provided progress is maintained on other aspects of plant breeding, it may well be possible to put together programmes. which take into account the nutritional aspects of crop residues.
McDowell: At a recent Centres week, representatives from Africa expressed a preference for hydride rather than selected varieties. This may relate to yield and quality of residues. For instance in maize stover yields of hybrid varieties were superior to open pollinated varieties.
Witcombe: It is probable that the choice is dictated by the primary economic factors of seed production. I do not think it likely that the quality of stover differs between hybrids and open pollinated varieties.
Pearce: The remaining question is the matter of collaboration between animal nutritionist and plant breeders. Animal nutritionists can distinguish between a number of straws with varying nutritional quality but the input of the plant breeder is needed to tell the animal nutritionist what is practically feasible.
McDowell: The question of the feeding value of crop residues is one that should concern all plant breeders in national programmes. as well as the international centres.
Jenkins: The workshop has been most stimulating and may be the first time that plant breeders and animal nutritionists have met to consider the question of crop residues. It is clear that in many situations farmers are interested in the value of these residues. I am sure we would all like to thank ILCA for organising this workshop and Capper and Reed for the original concept.
For further details log on website :
http://www.fao.org/Wairdocs/ILRI/x5495E/x5495e0j.htm#TopOfPage
General discussion - Session 5 Recommendations and future prospects for plant breeding to maintain or improve the nutritive value of crop residues
Onim: We need to arrive at a definition of what constitutes a crop residue. For instance, thinnings may be fed to animals before harvest.
Kossila: Even materials such as potato peelings are, in my opinion, crop residues.
Said: Byproducts are mostly fed with supplements, such as urea/molasses, which may influence intake. Clearly the methodology for intake determination needs to be standardised.
Berhane: I think that the general statement proposed for adoption by the meeting is too strongly worded. I do not believe that the CG centres should put more emphasis on crop residue value.
Van Soest: The statement does not diminish the importance of grain production in any way. However, it may not be appropriate to list priority crops for investigation of crop residues and there may be many important benefits from a particular variety before residue value should be considered.
Gupta: Attempts should be made to find morphological characteristics that are, associated with feeding values of crop residues.
Jenkins: It would be useful to have correlated traits with which plant breeders could work.
Van Soest: Whatever selection methods are chosen it is important that they are compatible with the objectives of the work.
Gupta: If the traits related to nutritive value were known even as many as 10,000 samples would not be too large a number in a plant breeding programme. I agree that one should avoid screening entire gene banks.
Jenkins: I believe it would be unwise to be specific on the scale of any evaluation programme.
Van Soest: It is usually necessary to use plant criteria including grain yield to narrow down the number of entries that can be fully evaluated in the laboratory to about 200. Subsequently residues from no more than 12 varieties could be subjected to full animal evaluation. In addition one could include a few parent lines with promising value. Perhaps I should also mention that work on an European Community project being conducted in the Netherlands has shown that varieties of maize grown in Europe have digestibilities of residues 10 units higher than those grown in the USA and this does not appear to be an environmental effect.
Berhane: In my previous comments I was not questioning the practical value of investigating variation in crop residue quality. However I would not see this as a primary responsibility of the CG centres, which should concentrate on grain yield and grain quality. To bring in crop residue value as an index of selection would not serve the immediate mandate of CIMMYT to increase yields of wheat and maize.
Fussell: The question of whether crop residues are important needs to be put to the ultimate user of new varieties, the farmer. More information is needed as to what is happening at the farmer level, through more feedback from extension services.
Witcombe: Ground-level surveys are needed, involving cooperation between economists and animal nutritionists, in order to obtain farmers' perceptions regarding the acceptability of new varieties. This should form a major recommendation.
Little: We need to know the base-line considerations of farmers concerning crop residues.
Onim: There appears to be a need to introduce animal nutritionists at crop research centres.
McAllan: It would concern me that the number of materials to be evaluated may exceed the capacity of animal nutrition facilities. Should animal nutritionists be in a monitoring or collaborative role?
Fussell: I would suggest looking at current varieties first. For example in West Africa only five or six millet varieties would need to be fully evaluated.
Reed: Perhaps we are putting too much emphasis on the need for farmer surveys. For instance we already know that the digestibility of barley straw in the Ethiopian highlands is 55% whereas in Europe it is only 35%. Information is already available for groundnut residues in Senegal. I consider it more important to deal with the effects of crop management on residue values so that they are at least capable of maintaining the animals.
Little: Emphasis needs to be placed on finding an appropriate method of evaluation for particular crops. Subsequently such tests could then be run by laboratory technicians.
Van Soest: I think that one will need more than one parameter to effectively identify varieties with superior crop residue value. The use of plant criteria followed by investigations of crop residue value would seem to be the best means of tackling the large number of entries available.
Jenkins: It would be useful to have contributions from national programme representatives.
Kebede: In Ethiopia I consider that we must continue to give priority to grain production, to consider residue value may be a luxury. Yet this workshop has been an eye-opener and, provided progress is maintained on other aspects of plant breeding, it may well be possible to put together programmes. which take into account the nutritional aspects of crop residues.
McDowell: At a recent Centres week, representatives from Africa expressed a preference for hydride rather than selected varieties. This may relate to yield and quality of residues. For instance in maize stover yields of hybrid varieties were superior to open pollinated varieties.
Witcombe: It is probable that the choice is dictated by the primary economic factors of seed production. I do not think it likely that the quality of stover differs between hybrids and open pollinated varieties.
Pearce: The remaining question is the matter of collaboration between animal nutritionist and plant breeders. Animal nutritionists can distinguish between a number of straws with varying nutritional quality but the input of the plant breeder is needed to tell the animal nutritionist what is practically feasible.
McDowell: The question of the feeding value of crop residues is one that should concern all plant breeders in national programmes. as well as the international centres.
Jenkins: The workshop has been most stimulating and may be the first time that plant breeders and animal nutritionists have met to consider the question of crop residues. It is clear that in many situations farmers are interested in the value of these residues. I am sure we would all like to thank ILCA for organising this workshop and Capper and Reed for the original concept.
For further details log on website :
http://www.fao.org/Wairdocs/ILRI/x5495E/x5495e0j.htm#TopOfPage
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